1. Field of the Invention
The invention relates to technologies of conveying a sheet, and in particular to technologies of purging it.
2. Background
Typically, sheet conveyance devices built into image forming devices, such as printers and copiers, sheet feeder devices, or post-processing devices, convey sheets consecutively along a single path to allow sequential processing, such as printing, to be performed with respect to the sheets, thus achieving high-speed processing of several dozen pages per minute (ppm) or more.
If a failure such as a paper jam or a defect in image quality occurs with respect to a sheet conveyed through the path, a sheet conveyance device usually forces other conveyed sheets to stop at appropriate locations on the path. See for example JP 2005-221518. Removal from the path of all the sheets that the device stops is required to make the device resume conveying other sheets. However, leaving all removal to a user is a burden on the user.
Conventional sheet conveyance devices include a type that automatically discharges a conveyed sheet if an image forming device or the like aborts processing the sheet. Hereinafter, such discharging of a sheet is referred to as “purging”, and in particular discharging upon detection of a cause of a processing abortion such as a paper jam is referred to as “pre-purging”. A sheet to be purged is generally purged to a dedicated tray that is different from an output tray originally intended as a destination of conveyance. See for example JP 2014-119634.